Coastal ecotourism and industrial impacts on Indo-Pacific humpback dolphins in Hong Kong

Abstract

One of the largest populations of the Indo-Pacific humpback dolphin (Sousa chinensis) resides in the Pearl River Delta (PRD) area. The coastal affinity of this species makes them particularly exposed to coastal tourism and industrial activities. Recently, the PRD area in Hong Kong has experienced a rapid increase in coastal development projects, leaving limited natural habitats available to the dolphins in the area. A recent population trend projection, suggesting a significant decline in numbers of the PRD animals, has heightened the conservation concern. This study investigated movement patterns of humpback dolphins observed from strategic land-based platforms in areas designated as high importance to the species. Analyses of theodolite-obtained data evaluated movement (e.g. directionality, re-orientation, speed, etc.); focal behavioural events and behavioural states of the dolphins to understand their 'natural' habitat use in these important areas as well as movement and behavioural response indicators relative to unregulated dolphin-watch tourism and industrial anthropogenic activities. Spatiotemporal patterns in dolphin abundance/distribution, movements, and habitat preference were also compared among the different study sites to determine difference in areas with and without high anthropogenic activities. Spatial explicit and uncorrelated random walk models were used to provide quantitative information about individual/group movement/response patterns. Geographic occurrence of dolphins relative to different anthropogenic activities in the different study sites were analysed using ESRI ArcMap GIS. Type and intensity of anthropogenic activities can directly affect the individual and population fitness. The results of this study provide local conservationists and managers with valuable feedback on ecotourism management and impact concerns of industrial development as well as much needed biological monitoring and implementation of mitigations measures to protect the humpback dolphins that depend year-round on the PRD coastal habitat.